Combustion systems generally mix one or more fluids, such as fuel and air, before providing the same to a combustion chamber. A combustion nozzle assembly may be provided upstream of the combustion chamber and may provide fuel and air mixtures to the combustion chamber. Therefore, the combustion nozzle assembly may mix fuel and air in suitable proportions to operate the combustion chamber under suitable parameters. The mixing may be performed by flowing fuel in a particular conduit and by flowing air in another conduit and mixing the two through appropriate orifices. Accordingly, the mixing proportions as well as other parameters may be controlled by modulating, such as baffling, the flow of one or more of the fuel and air through the orifices.
In certain aspects, the mixing of two fluids through an orifice may be controlled by providing obstructions to the flow of one or more of the two fluids in proximity of the orifice. Therefore, the obstruction to the flow of one or more of the two fluids may be controlled by the level of perturbation of the flow of the one or more of the two fluids when obstructed by the obstruction.
In the case of combustion nozzle assemblies, an apparatus for the control of fuel and air mixtures may be used to control the fluctuation of fuel in a fuel conduit prior to mixing with air, thereby controlling the fluctuation of a heat released during combustion. These fluctuations are also commonly referred to as q-prime. Similarly, apparatus for the control of air velocity and pressure fluctuation in proximity of a mixing orifice upstream of the combustion chamber may be provided to control the fuel air mixture or proportions. These pressure fluctuations are also commonly referred to as p-prime.
In certain aspects, the control apparatus that may be utilized to control the fuel and air mixture upstream of the combustion chamber may need to operate at relatively high temperatures. In certain cases, the high temperature operation may limit the choice of apparatus that may be used for the purposes of controlling the fuel air mixture. Commonly, the temperature of operation may exceed the Curie temperatures of commonly used ferroelectric materials.